The invention relates to a fastening element for securing a rod-shaped element to a shaft of a medical instrument. A bracket at least partially engages the circumference of the rod-shaped element, where the bracket can be inserted in a side opening of a portion of the shaft. A tensioning mechanism draws the bracket out of the opening, whereby the rod-shaped element is securely clamped to the shaft portion.
The invention also relates to a medical instrument making use of such a fastening element.
A fastening element and an instrument of the mentioned type are disclosed in the U.S. Pat. No. 5,713,869.
With medical instruments, there is frequently the need to use additional instruments or components, which normally are configured to be substantially rod-shaped, i. e. elongated as the shaft of the instrument itself. This extends the functions of the medical instrument.
A rod-shaped element in the sense of the present invention is for example an irrigation shaft, a shaft for optics or an instrument shaft for a further auxiliary instrument, such as cutters, pincers or a canula, a probe, an electrode support or the like, only to name a few. xe2x80x9cRod-shapedxe2x80x9d is to be understood independent of the outer contour and independent of whether the element is hollow (tubular) or is solid.
In the scope of the present invention, the shaft of the medical instrument can be a tubular shaft, for example of a laryngoscope. In such a case, it is desirable that the rod-shaped element be secured to the interior of the shaft, so that the additional rod-shaped element does not block the view or does not enlarge the outer diameter of the tubular shaft of the medical instrument.
In the scope of the present invention, however, the shaft of the medical instrument can also be configured such that the shaft wall is not closed about the periphery as with a tubular shaft, but is open to the side.
The known fastening element of the mentioned U.S. Pat. No. 5,713,869 comprises a bracket, which can be inserted from the outside into the interior of the shaft through a side opening, a movable lever with a cam is provided as a tensioning mechanism for drawing the bracket in the direction out of the shaft. By moving the lever out of a position in longitudinal direction of the fastening element into a position transversely to the longitudinal direction, the cam engages with the outer wall of the shaft and the bracket is drawn outwardly by rolling the cam against the outer wall of the shaft.
The tensioning mechanism of the known fastening element, however, has the drawback that the tensioning mechanism is not variable, so that the known fastening element is suited only for clamping a rod-shaped element with a defined diameter. If a rod-shaped element is used which is too thin, actuating the lever does not draw the bracket far enough out of the opening to securely clamp the rod-shaped element. If the rod-shaped element is too thick, the lever can not be actuated in some circumstances and the bracket can then not be fixed in the tensioned state. In addition, the danger exists with rod-shaped elements of larger diameter that the clamping force when applying the lever is excessive, so that the rod-shaped element is bent or crushed. Especially, when the rod-shaped element contains the endoscope optics, the danger exists that the optics are damaged by excessive clamping forces.
A fastening element is also known from the German Patent DE 41 37 426, which in contrast to the above mentioned fastening element is inserted in longitudinal direction of the instrument shaft into a proximal end opening and is clamped there with a jaw in the manner of a screw clamp. A seat for retaining a rod-shaped element is provided in the fastening element, which includes a leaf spring for clamping the rod-shaped element in the seat. However, this represents insufficient means for clamping the element to the shaft.
The portion of the shaft in which the opening is provided for inserting the bracket can be the wall of the shaft itself according to the present invention or the shaft portion can be formed as a holder connected to the shaft.
The object of the present invention is to provide such a fastening element of the mentioned type with which rod-shaped elements of various cross sections can be securely fastened to a portion of the shaft without damage.
According to the present invention, this object is achieved by a fastening element for securing a rod-shaped element on a shaft of a medical instrument, comprising a bracket for engaging at least partially a circumference of said rod-shaped element, said bracket being insertable in a side opening of a shaft portion of said shaft; a tensioning mechanism which when actuated draws said bracket in a direction out of said opening for clamping said rod-shaped element onto said shaft portion, wherein said tensioning mechanism is configured such that the clamping force of said tensioning mechanism for clamping said rod-shaped element is continuously adjustable when actuating said tensioning mechanism.
According to the present invention this object is also achieved by a medical instrument, comprising a shaft having at least one side opening in a shaft portion of said shaft, a fastening element for securing a rod-shaped element on said shaft, said fastening element further comprising a bracket for engaging at least partially a circumference of said rod-shaped element, said bracket being insertable in said side opening of said shaft portion of said shaft, a tension mechanism which when actuated draws said bracket in a direction out of said opening for clamping said rod-shaped element onto said shaft portion, wherein said tensioning mechanism is configured such that the clamping force of said tensioning mechanism for clamping said rod-shaped element is continuously adjustable when actuating said tensioning mechanism.
According to the present fastening element, a type of clamping adapter is provided with which a rod-shaped element can be securely clamped to the shaft of a medical instrument with simple handling. The bracket of the fastening element is inserted through the opening in a portion of the shaft, where the rod-shaped element can then be inserted into the bracket. The tensioning mechanism is then actuated and the bracket is continuously drawn in the direction out of the opening in the shaft portion until the rod-shaped or tubular element is clamped to the shaft. Due to the continuous action of the tensioning mechanism, the fastening element is universally applicable to different rod-shaped elements of various cross sectional dimensions. The present fastening element now makes it possible for example to secure a flushing shaft or a shaft for optics. With the present configuration of the fastening element, a high clamping force for securing the rod-shaped element is achieved, however, being adjustable by the hand of the user, so that differently dimensioned rod-shaped elements can be clamped to the portion of the shaft with about the same clamping force. The rod-shaped element does not deform and is not damaged, despite a high clamping force.
The object underlying the present invention is thus completely achieved.
In a preferred embodiment, the tensioning mechanism comprises a screw mechanism comprising an actuator element which is rotatable about a center axis of the fastening element, whose rotary motion is converted into a motion of the bracket in an axial direction of the fastening element.
A tensioning mechanism having a screw mechanism for tightening the bracket has the advantage that the hand force of the user when actuating the tensioning mechanism is well controllable, because the user can easily determine the achieved clamping force through the increasing difficulty in turning the actuator element. In addition, such a screw mechanism can be easily configured to be self-locking, so that the rod-shaped element can not loosen after tightening the bracket.
In a further preferred embodiment, the tensioning mechanism comprises a retainer for the bracket movable in axial direction of the fastening element, to which the bracket is secured and which is connected to the rotatable actuator element through a threading engagement.
The advantage is that a screw mechanism requiring few parts is provided for converting the rotary movement of the actuator element into a translational movement of the bracket, which additionally is self-locking.
In a further preferred embodiment, the fastening element comprises an abutment for substantially form-locking engagement with the contour of the shaft portion.
The advantage is that a particularly high clamping force can be applied for clamping the rod-shaped element to the shaft portion due to the substantially form-locking engagement with the abutment, without damaging the shaft portion through point loads or edges on the fastening element.
In a further preferred embodiment, the tensioning mechanism comprises a turning knob surrounding a first non-rotatable bushing, the bushing compring a base portion provided with an opening for the bracket, whose outer side engages with the shaft portion, the first bushing enclosing the retainer, formed as a second bushing, the turning knob being fixably connected to a pivot pin, extending through the retainer, which is engaged with the retainer through a threading.
This configuration of the present fastening element ensures a reliable function of the fastening element, easy operation and in addition a small size, which is desired for medical instruments. The base portion of the first bushing can be formed as the mentioned abutment in advantageous manner.
In a further preferred embodiment, the bracket comprises a radially elastic retaining section formed to be partially circularly expanded, into which the rod-shaped element can be inserted, the retaining section having a diameter which is larger than the transverse dimension of the opening in the shaft portion.
The feature has the advantage that the fastening element after having been placed in the opening on a portion of the shaft is locally fixed in self-holding manner to the shaft due to the circularly expanded, radially elastic retaining section, this before the rod-shaped element is inserted into the bracket and the bracket tightened down. The fastening element can thus be inserted into the opening of the shaft portion as a type of clip and will not fall out even when the rod-shaped element is not inserted into the bracket. The handling operation of the fastening element for securing the rod-shaped element is therefore substantially improved.
In a further embodiment, the bracket is formed with small material thickness, preferably in the form of a band.
The advantage is that the bracket does not represent an obstacle taking up space, because it does not substantially project radially from the rod-shaped or tubular element.
In a further preferred embodiment, the bracket extends in longitudinal direction of the rod-shaped element over a portion of same.
The advantage is that the rod-shaped element can be secured to the shaft of the instrument even with a single fastening element according to the present invention, without the element being able to pendle or tip. A width of the bracket of about 0.5 to 1 cm is already sufficient, without the invention being limited thereto.
In a further preferred embodiment, a counterplate is provided on the bracket at the side of the opening facing the rod-shaped element.
With such a counterplate, it can be advantageously avoided that the rod-shaped element, when having a very small diameter, is partially drawn into the opening with its outer periphery when tightening the fastening element. The counterplate is preferably configured such that it closes the opening and optionally acts as a form-locking counter-support for the rod-shaped element.
In a preferred embodiment of the instrument, the shaft portion is formed by the wall of the shaft itself.
This can be of advantage for an instrument having a tubular shaft, where the rod-shaped element is to be clamped in the interior of the tubular shaft with the fastening element and where in such a case only an opening needs to be provided in the wall of the tubular shaft in simple constructive manner.
However, it is also preferred when the shaft portion is a holder connected to the shaft.
Such a holder can be fixably connected to the shaft of the instrument or as described in a further preferred embodiment be configured to be secured at different locations on the shaft. The holder element can for example be formed as a clamping member itself with clamping means through which the holder element can be clamped at various locations on the shaft.
In a preferred embodiment, the opening in the shaft portion is configured as a slotted hole, whose axis extends in the longitudinal direction of the shaft.
This has the advantage that the fastening element can be attached at various positions in the longitudinal direction of the shaft of the instrument, so that the rod-shaped element can also be clamped at various positions on the instrument.
In a further preferred embodiment, a plurality of openings distributed on the shaft portion are present.
The advantage is that the rod-shaped element can be secured at various positions on the shaft with the corresponding arrangement of the openings.
In a further preferred embodiment of the instrument, the shaft portion comprises at least partially a curved section which is curved with respect to the longitudinal direction of the shaft, where the opening is formed as a slotted hole and extends at least over the curved section of the shaft portion.
The advantage is that the rod-shaped element can be secured on the shaft at different angular orientations with respect to the longitudinal direction of the shaft. This embodiment is especially suitable for the case that the rod-shaped element contains observation optics. With the different possible angular positions between the optics and the shaft, different view directions can be realised relative to the longitudinal direction of the shaft.
Further advantages can be taken from the following description and the attached drawings. It will be understood that the above mentioned features and those to be discussed below are not only applicable in the given combinations, but may be used in other combinations or taken alone without departing from the scope of the present invention.
Embodiments of the invention are illustrated in the drawings and will be described in more detail below: